Medium [CVE-2026-11793] stack buffer overflow in checkprefix algorithm id parsing
This medium-severity Red Hat Linux advisory covers CVE-2026-11793 affecting Red Hat Directory Server 11, Red Hat Directory Server 12, Red Hat Directory Server 13.
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Summary
A stack buffer overflow flaw was found in 389 Directory Server. The checkPrefix() function in pw.c copies an attacker-controlled algorithm ID into a 256-byte stack buffer without bounds checking when parsing reversible-encrypted attribute values.
An attacker with Directory Manager privileges can crash the LDAP server by storing a crafted credential with an oversized algorithm ID. FORTIFY_SOURCE mitigates this to denial of service only.
Red Hat severity: Low — CVSS 4.9 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-121.
Affected Red Hat products: Red Hat Directory Server 11; Red Hat Directory Server 12; Red Hat Directory Server 13; Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Will not fix / out of support: Red Hat Enterprise Linux 6.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- Restrict Directory Manager access. Monitor cn=config attributes (nsDS5ReplicaCredentials, nsDS5ReplicaBootstrapCredentials) for abnormally long values. Restrict LDAP administrative access to management networks or localhost (LDAPI).
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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